Charged particle beam device for scanning a sample using a charged particle beam to inspect the sample

ABSTRACT

There is provided a substrate inspection device which uses a charged particle beam and is capable of more quickly extracting a defect candidate than ever before. The configuration of the substrate inspection device is such that a substrate having a circuit pattern is irradiated with a primary charged particle beam, the substrate is moved at a constant speed or at an increasing or a decreasing speed, a position resulting from the movement is monitored, the position of irradiation with the primary charged particle beam is controlled according to the coordinates of the substrate, an image in a partial region on the substrate is captured at a speed lower than the velocity of the movement, a defect candidate is detected based on the captured image, and the detected defect candidate is displayed in a map format.

RELATED APPLICATIONS

This application is the U.S. National Phase under 35 U.S.C. §371 ofInternational Application No. PCT/JP2009/004205, filed on Aug. 28, 2009,which in turn claims the benefit of Japanese Application No.2008-234270, filed on Sep. 12, 2008, the disclosures of whichApplications are incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a charged particle beam device forinspecting a substrate on which a circuit pattern is formed, by using acharged particle beam. The substrate as an inspection sample is such asa semiconductor substrate for a semiconductor device or a deflectionarray substrate for a liquid crystal display.

BACKGROUND ART

In a manufacturing process for a substrate with a circuit pattern for asemiconductor device or a liquid crystal display, a defect such as abreak, a short circuit, a flaw, or a foreign material affects theperformances of the semiconductor device or the liquid crystal displaymanufactured from the substrate. For this reason, it is important toearly detect such a defect. Along with finer circuit patterns, theinspection device, which uses an electron beam and to which thetechnique of an electron microscope is applied, has been put intopractical use, as well as an optical inspection device using reflectedlight.

Defect detection with the inspection device using such a chargedparticle beam is performed by capturing images of a region with arepetitive pattern and an adjacent region thereof and comparing theimages with each other. Namely, the defect detection is performed basedon knowledge that the above circuit pattern has a feature repeating thesame pattern. Alternatively, there is used a defect detecting method ofstoring an image with a defect-free pattern in a device as a referenceimage and comparing an image to be detected with the reference image. Insuch a defect detection, pixel(s) different in signal intensity such asbrightness are extracted from the captured image by the pixel. A pixelin which signal intensity exceeds a predetermined threshold is taken asa defect candidate and the representative coordinates thereof isobtained. The reason the image is taken as a defect candidate is thatnoises are superimposed on the image itself due to various reasons andcan be detected as a defect. An operator visually views an image havinga detect candidate to determine whether the image is a true defect.

As described above, in the defect detection, images to be compared witheach other since are subjected to a computing process, an inspectionspeed of the inspection device is basically rate-determined by a speedat which an image is captured. However, an area where the inspectiondevice using the charged particle beam can image at one time is verysmall compared with an area of a substrate to be inspected, so thatvarious methods for reducing an inspection time or improving aninspection speed without decreasing inspection accuracy are attempted.

As an example, there has been known a sampling method which reduces thenumber of scanning stripes for capturing an image in an image pickupprocess (hereinafter referred to as a swath sampling). For example,Documents 1 or 2, or Non-Patent Document 2 listed below discloses aninspection device with a function for automatically setting the numberof scanning stripes to be set in a chip according to the setting valueof a sampling ratio by setting a sampling ratio in setting an inspectionregion. According to the swath sampling, an imaging area on thesubstrate to be inspected although is reduced in comparison with ageneral inspection method, provided the imaging area is sampled by astatistically meaningful method, a problem in manufacture of thesubstrate can be analyzed by analyzing the distribution of the detecteddefect candidate or the defect candidate in detail.

Patent Document 3 and Non-Patent Document 1 listed below disclose areference image averaging (RIA) technique in which, since the swathsampling has a relationship of trade-off between a signal-to-noiseration (S/N) and an image capturing speed, a defect determination methodis devised to realize a high-speed inspection. However, a more improveddevice is demanded to detect an image at a high-speed.

PRIOR ART DOCUMENTS Patent Document

-   Patent Document 1: Japanese Patent Application Laid-Open No.    2000-161932-   Patent Document 2: Japanese Patent Application Laid-Open No.    2002-026093-   Patent Document 3: Japanese Patent Application Laid-Open No.    2005-274172-   Non-Patent Document 1: T. Hiroi et al, “Robust Defect Detection    System Using Double Reference Image Averaging for High Throughput    SEM Inspection Tool,” 2006 IEEE/SEMI Advanced Semiconductor    Manufacturing Conference, pp. 347-352.-   Non-Patent Document 2: M. Ikota et al, “In-line e-beam inspection    with optimized sampling and newly developed ADC,” Proceedings of    SPIE Vol. 5041 (2003), pp. 50-60.

SUMMARY OF INVENTION Technical Problem

In the swath sampling, it is known that up to 10% sampling is astatistically meaningful sampling ratio, from evaluation experimentresults disclosed in Non-Patent Document 2. This corresponds to a speedincrease of 10 times. Furthermore, provided the defect determinationmethod described in Non-Patent Document 2 is combined with the up to 10%sampling described above, it is possible to realize a speed increase ofapproximately 20 times.

A typical user needs an inspection in which 70% (effective area) of a300 mm diameter wafer can be inspected by a 35-nm-pixel 200 Mpps clockin one hour. Under this condition, if any speed increasing method is notused, the inspection requires approximately 80 hours. For this reason, aspeed increase of approximately 20 times that can be achieved by aconventional swath sampling is not enough, so that a furtherspeed-increase of approximately 4 times to 10 times is required.

An object of the present invention is to provide a charged particle beamdevice and a substrate inspection device using the charged particle beamcapable of more quickly extracting a defect candidate than ever before.

Solution to Problem

The above object can be achieved by an inspection device with a functionof setting a predetermined inspection stripe in a sample to beinspected, the sample having plural regions where predetermined patternsare formed respectively, capturing plural partial region-images in theinspection stripe, and executing an inspection using the capturedpartial region-images. Put another way more simply, an inspectionskipped region where an image is not captured, is set in the area of theinspection stripe. The inspection device according to the presentinvention has a function of sampling plural partial inspection regionsfrom the sample to capture the partial inspection images while moving asample-stage on which the above sample to be inspected is placed. Theirradiation in the inspection stripe with a primary charged particlebeam is performed by moving the stage and scanning sequentially thepartial inspection regions with the charged particle beam in a directionintersecting with a sample stage-movement direction. Accordingly, theabove sampling function is realized by executing a beam scanningdeflection control in accordance with the velocity of samplestage-movement so that only the partial inspection region aresequentially irradiated with the primary charged particle beam.

This allows an inspection to be executed at a higher speed than everbefore by performing an inspection by sampling only the partialinspection regions interesting an operator, i.e., region of interest(ROI) (hereinafter referred to as “ROI inspection”) or by a simplesampling. A typical ROI region includes, for example, a corner portionand an edge portion of a memory mat formed in a semiconductor device orall the pattern portions excluding non-pattern portion in a case where apattern density is low.

In the embodiment of the present invention, in order to increase theinspection speed, it is desirable to move the stage at a speed higherthan an image capturing velocity with a charged particle column forexecuting the beam scanning deflection control. In this case, an imagecapturing timing since is asynchronous with the velocity of the samplestage movement, a beam deflecting-back deflection control is also usedto avoid displacement in beam irradiation positions resulting therefrom.

The inspection device of the present invention may have a managementconsole for displaying a screen for setting the dimension of the aboveROI region and a repetitive pitch. Furthermore, the inspection devicemay compute the above mentioned stage movement velocity and the amountof deflection control of the primary charged particle beam based oncontrol parameters such as values for setting the dimension of the ROIregion and the repetitive pitch. The inspection device captures imagesusing the computed values, executes a trial inspection by comparing theimages with each other, and sets an inspection recipe by determiningwhether an inspection condition is accepted.

Advantages of the Invention

According to the present invention, the charged particle beam devicecapable of extracting a defect candidate at a higher speed than everbefore can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical section showing the configuration of a substrateinspection device;

FIGS. 2A to 2D are plan views of a wafer;

FIGS. 3A and 3B are flowcharts showing the procedure for creating arecipe and the procedure for inspection;

FIG. 4 shows an example of a screen displayed on the screen of aconsole;

FIG. 5 are enlarged views of a plurality of dice shown in FIG. 2A;

FIG. 6 is graphs showing a change in stage velocity with time;

FIG. 7 shows a screen displayed at a trial inspection;

FIG. 8 is a schematic diagram describing a method of determining adefect;

FIG. 9 is a sequence diagram for capturing an image used for acomparison inspection;

FIG. 10 is a graph showing a change in the amount of obtained signalswith time;

FIG. 11 is graphs showing a relationship between an image capturingregion and a deflection voltage applied to a deflector;

FIGS. 12A, 12B and 12C show a part of layout of an sample;

FIGS. 13A to 13B are plan views of a memory mat showing a procedure forsampling; and

FIG. 14 is a diagram showing the inspection of a partial region of thememory mat 32.

DESCRIPTION OF EMBODIMENTS

The embodiment of the present invention is described below withreference to drawings.

Embodiment 1

FIG. 1 is a vertical section showing a configuration of an inspectiondevice according to the present embodiment. The inspection device of thepresent embodiment is the one to which a scanning electron microscope isapplied. The principal units are contained in a vacuum container. Thisis because a substrate such as a semiconductor wafer is irradiated witha primary charged particle beam. The inspection device of the presentembodiment includes a charged particle column comprising an electronsource 1 for irradiating a wafer 6 placed on a sample table 9 with aprimary charged particle beam 2, a detector 13 for detecting a secondarycharged particle 10 such as secondary electrons generated on the waferor a reflection electrons from the wafer to output a signal as asecondary charged particle signal. The inspection device furtherincludes the followings: an X-Y stage 7 for moving the sample table 9 inan X-Y plane; a defect determination section 17 for imaging thesecondary charged particle signal output from the column, comparing theimage obtained from the secondary charged particle signal with areference image and extracting a pixel or pixels having a difference inthe amount of signals as a result of a comparison therebetween, namelyextracting the pixel or pixels as a defect candidate; and a generalcontrol section 18 for generally controlling the charged particlecolumn, the X-Y stage 7, and the defect determination section 17. TheX-Y stage 7 and the sample table 9 are held in a vacuum sample chamber.

Since the primary charged particle beam 2 is greatly narrowed by anobject lens 4 to converge the energy of the primary charged particlebeam 2 onto the wafer 6, the diameter of the primary charged particlebeam 2 is significantly small on the wafer 6. The primary chargedparticle beam 2 is deflected by a deflector 3 in the predeterminedregion on the wafer 6 to scan the wafer 6. The position of movement byscanning is synchronized with the detection timing of a secondary signal10 to form a two dimensional image.

A circuit pattern is formed on the surface of the wafer 6. However thewafer 6 since is made of various materials, the wafer 6 may produce acharging phenomenon in which an electric charge is accumulated on thewafer by the irradiation of the primary charged particle beam 2 on thewafer 6. The charging phenomenon since changes the brightness of animage or deflects the orbit of incident primary charged particle beam 2,a charging control electrode 5 is provided in front of the wafer 6 tocontrol field strength.

Before the wafer 6 is inspected, a reference sample 21 is irradiatedwith the primary charged particle beam 2 to form an image, thencalibrations for the coordinates of the primary charged particlebeam-irradiating position and a focal point are executed respectively.As described above, the diameter of the primary charged particle beam 2is significantly small, the scanning width of the deflector 3 is muchsmaller than the size of the wafer 6 and the image formed by the primarycharged particle beam 2 is vary small. For this reason, the wafer 6 isplaced on the X-Y stage 7 before the inspection, an coordinatecalibration use alignment mark on the wafer 6 is detected from an imagewith a comparatively low magnification rate using an optical microscope20, the X-Y stage 7 is moved to position the alignment mark under theprimary charged particle beam 2, thereby calibration of the coordinatesis executed.

A calibration for focus is performed by the followings: measuring theheight of the reference sample 21 with a Z-sensor 8 for measuring theheight of the wafer 6, next measuring the height of the alignment markon the wafer, and adjusting excitation strength of the object lens 4 sothat a focus range of the primary charged particle beam 2 narrowed bythe object lens 4 includes the alignment mark.

A large number of the secondary signals 10 are caused to strike on areflection board 11 with a secondary signal reflector 12 to detect asmany of the secondary signals 10 generated on the wafer 6 as possible.Second secondary electrons generated with the reflection board 11 aredetected with the detector 13.

The general control section 18 controls the above-mentioned operationsfor configuration as to the coordinates and focus. The general controlsection 18 sends a control signal (a) to the deflector 3 and sends acontrol signal (b) of the excitation strength to the object lens 4. Thegeneral control section 18 receives a measurement (c) of height of thewafer 6 sent from the Z-sensor 8 and sends the X-Y stage 7 a controlsignal (d) to control the X-Y stage 7.

The signal detected by the detector 13 is converted into a digitalsignal 14 by an AD converter 15.

The defect determination section 17 generates an image from the digitalsignal 14, compares the image with a reference image, extracts aplurality of pixels having a difference with respect to the referenceimage in brightness as defect candidates, and sends the general controlsection 18 a defect information signal (e) including the coordinates onthe wafer 6 corresponding to the image signal.

The inspection device according to the present embodiment includes aconsole 19. The console 19 is connected to the general control section18 to display a defect image on the screen of the console 19. Thegeneral control section 18 computes the control signal (a) for thedeflector 3, the control signal (b) of the excitation strength for theobject lens 4, and the control signal (d) for controlling the X-Y stage7. The console 19 is equipped with a key board for inputting the aboveinspection conditions and a pointing device such as a mouse. A deviceuser operates the key board and the pointing device to input theinspection conditions.

FIGS. 2A to 2D are plan views of the wafer 6 to be inspected. As shownin FIG. 2A, the semiconductor wafer 6 is a disk-shaped silicon substratewith a diameter of 200 mm to 300 mm and a thickness of approximately 1mm. A plurality of dices 30 to be a semiconductor chip is formed fromthe wafer. The size of the wafer 6 has been already standardized, sothat the number of the dice 30 formed on the single wafer 6 isdetermined depending on the size of the die 30. As shown in FIG. 2B, thesingle die 30 includes a plurality of memory mat groups 31 andmemory-mat peripheral circuit group excluding the memory mat groups 31.For a general memory device, a pattern layout of the die 30 isconfigured by four memory mat groups 31. As shown in FIG. 2C, eachsingle memory mat group 31 is formed of a plurality of memory mats 32.For a general memory device, the memory mat group 31 is formed ofapproximately 100×100 memory mats 32. As shown in FIG. 2D, the memorymat 32 is comprised of a plurality of memory cells 33 with repeatabilityin the two-dimensional direction. Several million memory cells 33 formthe single memory mat 32. Each of the memory cells 33 can be a hole (acontact hole or a via hole) formed in the insulation film or the holecan be plugged with a wiring material (referred to as a plug). Adetermination as to what state the wafer is inspected depends on acondition that the wafer is inspected under what production process of asemiconductor device.

Prior to inspection, a recipe for determining inspection conditions andan inspection procedure is formed. FIGS. 3A and 3B are flow chartsshowing the procedure for creating a recipe and the inspection procedureconducted along the set recipe respectively. In FIG. 3A, the generalcontrol section 18 reads a previously created and stored standardrecipe. In step 301, the wafer 6 to be inspected is loaded into theinspection device. The general control section 18 starts a process forreading the standard recipe and loading the wafer 6 with instructionsinput by the operator using the console 19, namely the instructions actas a trigger for starting the process. The loaded wafer 6 is placed onthe sample table 9. In step 302, the general control section 18 sets thefollowings: optical conditions such as the voltage applied to theelectron source 1, the excitation strength of the object lens 4, thevoltage applied to the charging control electrode 5, and the currentapplied to the deflector 3 based on the read standard receipt; thegeneral control section 18 sets alignment conditions for obtainingcorrection between the coordinates with reference to the alignment markof the wafer 6 and the X-Y stage 7 of the inspection device based on theimage of the reference sample 21; the general control section 18 setsinspection region information indicating a region to be inspected on thewafer 6, and sets calibration conditions for registering both ofcoordinates used for capturing the image for adjusting the amount oflight of the image and the initial gain of the detector 13.

The corner portion of the memory mat 32 shown in FIG. 2D is liable tocause a defect on the production process because the corner portion is aboundary between a region where a large number of the memory cells 33with repeatability exists and a region where the memory cell 33 withrepeatability does not exist. Since a material is different between theregions where the memory cell 33 with repeatability exists and does notexist, if a defect inspection is performed by comparing the image at thecorner portion of the memory mat 32 captured without changing theelectro-optical condition with the image at the region excluding thecorner portion, the memory cell that is not actually defective may beextracted as a defect by mistake because pixels are different inbrightness between the corner portion and the region excluding thecorner portion.

Therefore, in step 303, in order to inspect the corner portion of thememory mat 32 as shown in FIG. 2D, the corner portion is selected bydisplaying the pattern layout of the wafer 6 on the screen of theconsole 19 and surrounding the region of corner portion of the memorymat 32 by a square on a GUI screen. In step 304, the optical conditionsfor imaging the corner are set.

Actually, prior to the selection of corner portion of the memory mat,setting for an arrangement of the inspection stripe in any region of thedie is executed. In setting of the arrangement of the inspection stripe,the inspection stripe is set so that the desired corner portion of thememory mat is included, thereafter, the corner portion is selected instep 303.

In step 305, the inspection conditions are set to perform a trialinspection for confirming whether the set optical conditions arecorrect. In step 306, the trial inspection described later is executed.In step 307, the operator determines the result of the trial inspectionand confirms whether the inspection condition is correct. In step 308,if the operator determines that any of the inspection conditions needscorrecting, it is corrected in step 305. If the operator determines thatthe inspection conditions do not need correcting, the recipe is stored,the wafer 6 is unloaded and the formation of the recipe is finished instep 309.

FIG. 3B shows procedures for the inspection. In step 310, the recipestored in FIG. 3A is read. In step 311, the wafer 6 to be inspected isloaded into the inspection device. By using the console 19, andaccording to the specification of the wafer 6, the operator sets theoptical conditions to the general control section 18 by selecting orspecifying any suitable stripe to be actually used from among inspectionstripes capable of including the corner portion of the memory mat, aswell as a pixel dimension, and the number of times of line addition(step 312); the operator performs coordinate-alignment between thesemiconductor wafer 6 and the X-Y stage 7 (step 313), and performscalibration for adjusting the amount of light of the image (step 314).

In step 315, the defect inspection is started. The following series ofprocesses for the defect inspection is repeated until the inspection ofa predetermined die is finished: capturing an image in the selectedinspection region, comparing the captured image with the reference imageto extract a difference therebetween and determining the difference as adefect candidate (step 315); and storing the captured image with thedifference, the reference image and representative coordinates of thedefect candidate in a storage device (step 316). In step 317, when theinspection of a final die placed on the wafer 6 is finished, the wafer 6is unloaded.

FIG. 4 shows an example of an inspection region setting screen 40displayed on the screen of the console 19 when executing steps 303 and304 of the flow chart shown in FIG. 3A. A general schematic diagram ofthe die 30 shown in FIG. 2B is displayed in a map display region 41 onthe left of the screen 40 in FIG. 4. The image of the memory mat 32shown in FIG. 2D is displayed in an image display region 42 on the rightof the screen 40 in FIG. 4. The image on the coordinates specified inthe map display region 41 is displayed in the image display region 42.The screen 40 also displays an ROI condition setting section 43 forconfirming and changing the ROI conditions. When selecting any one ofobjects to be inspected in the ROI region (namely, the objects are a matcorner, simple sampling, a combination of the mat corner with the simplesampling, and any pattern portion to be selected from all patternportions in the case that densities of all pattern portions are low),for example, selecting the mat corner, detailed specification is neededabout mat corner portion to be inspected (for example, how many cornerpotions to be inspected among four corner portions or what percentage ofmemory mats among the corners of a plurality of memory mats to beinspected). Furthermore, when selecting the mat corner, thespecification is needed about what dimension to be inspected includingthe mat corner. The operator inputs various conditions into the ROIcondition setting section 43 to set an inspection region.

The corner portion of the memory mat 32 shown in FIG. 2D since has ahigh frequency as to defect, the inspection device of the presentembodiment has a function by which only a corner portion can be set asthe inspection region. A rectangular region 44 is specified on the imagedisplay region 42 in FIG. 4 to set the corner portion of the memory mat32 as the region to be inspected.

In a typical image comparison inspection, adjacent similar patterns arecompared with one another to extract a difference. However, in theinspection of a memory-mat portion, adjacent similar patterns since donot exist, a comparison inspection is performed by previously producinga reference defect-free image for the memory-mat portion (thedefect-free image is called as a golden image) and comparing the goldenimage with the captured image of the real mat portion to extract adifference therebetween.

The inspection region setting screen 40 shown in FIG. 4 shows an examplein which a “mat corner” is set as ROI, “four corners” as detail, “10 μm”as dimension, and “golden” as defect detection in the ROI conditionsetting section 43. This means that four corner portions of the memorymat 32 shown in FIG. 2D are selected as the ROI region, all the fourcorners of the memory mat 32 are inspected, an image capture-dimensionis 10 μm, and the golden image is produced. When the operator clicks an“IMAGE-CAPTURE” button, it is possible to capture images on afull-inspection stripe or a partial region including at least the ROIregion. A computing device included in the console 19 produces thegolden image by clipping partial images of the ROI region from thecaptured images, performing registration of the partial images and thenperforming averaging of them. The operator confirms the golden image inthe image display region 42 and pushes a “COMPLETION” button to storethe golden image in the recipe. The golden image may be produced by thedefect determination section 17.

Contents of the trial inspection shown in step 306 in FIG. 3A aredescribed below with reference to FIGS. 5 to 7. (a) of FIG. 5 is anenlarged view of the plurality of dice 30 shown in FIG. 2A. (b) of FIG.5 is a diagram further enlarging a part of the inspection stripe set ina certain die. In (a) of FIG. 5, reference numerals 51A, 51B, and 51Cdenote the plurality of dice 30 arranged adjacent to each other and areference numeral 52 represents the ROI scan region set in an inspectionstripe 53. In the present embodiment, the ROI scan region 52 is set inthe inspection stripe 53 with a width of L and a pitch of P between theadjacent ROI scan regions. An arrow passing through the center of theinspection stripe 53 shows the center in the y-direction of scan of theprimary charged particle beam and means the direction in which thesample stage 7 is moved.

In the trial inspection in step 306, the inspection device scans the ROIscan region 52 with the primary charged particle beam in a directionorthogonal to a direction of the X-Y stage 7 movement while moving theX-Y stage 7 in the direction indicated by the arrow along the pluralityof dice 51A, 51B, and 51C to capture images in the partial regionincluding the corner portion in the ROI scan region 52.

A detail configuration in the ROI scan region 52 is described below withreference to (b) of FIG. 5. As shown in (b) of FIG. 5, in the presentembodiment, the inspection stripe 53 is set so that six edges of thememory mat are included in the ROI scan region 52. For this reason, twosets of four corners formed at the memory mat-edges opposing each otherare included in the single ROI scan region 52. In (b) of FIG. 5, an ROIcapturing region 54 corresponding to the rectangular region 44 in FIG. 4is set in the eight memory mat corners in the ROI scan region 52.

The ROI scan region 52 and the ROI capturing region 54 are set byproviding information of inspection stripe arrangement on the die to beinspected and information of the ROI set on the inspection regionsetting screen 40 in FIG. 4 to all the dice to be inspected on the wafer6. The computing process for such setting is executed by the generalcontrol section 18. The width and length of the memory mat 32 aresubstantially constant in all the memory mats formed in the wafer andthe layout thereof is previously specified. For this reason, the generalcontrol section 18 can obtain information about coordinates of each ROIscan region 52 arranged on the inspection stripe 53 from informationabout the width L and the P of the ROI scan region 52, thereby cancontrolling beginning timing and end timing at which each ROI scanregion 52 is irradiated with the primary charged particle beam.

The captured image data in each ROI scan region 52 are transferred tothe defect determination section 17. The defect determination section 17extracts an image of the ROI capturing region 54 using information aboutthe layout of the memory mat and information about each ROI scan region52 obtained by the general control section 18, compares the capturedimage with the golden image described later to execute the defectinspection.

The golden image being the reference image for a comparison inspectionis produced by performing averaging of plural ROI capturing regions 54.The defect determination section 17 compares the golden image with thecaptured image in the plurality of the ROI capturing regions 54. Ifthere is a difference in brightness therebetween for each pixel, thepixel is extracted to produce an image as defect candidate. The image asa defect candidate and the coordinates of the defect candidate arestored in the defect determination section 17 as defect information andcan be displayed on the screen of the console 19.

Next, control of moving the stage in the ROI inspection according to thepresent embodiment is described below. In a conventional comparisoninspection, in order to capture the image on the inspection stripe 53shown in (a) of FIG. 5, the primary charged particle beam 2 isone-dimensionally scanned within a width of the inspection stripe 53 inthe direction substantially perpendicular to the direction indicated bythe arrow in (a) of FIG. 5 while continuously moving the X-Y stage 7 inthe direction indicated by the arrow. On the other hand, the inspectiondevice according to the present embodiment has only to scan only a partof the inspection stripe 53, i.e., only the ROI scan region 52 includingthe ROI capturing region 54, so that the movement velocity of the X-Ystage 7 can be made quicker correspondingly, than that in theconventional comparison inspection.

The reason the movement velocity of the X-Y stage 7 can be made quickerin the present embodiment is described below with reference to FIG. 6.(a) and (d) in FIG. 6 are schematic diagrams showing time distances onthe length L of the ROI scan region 52 and on the arrangement pitch P ina predetermined stage movement velocity. (b) and (e) in FIG. 6 areschematic diagrams showing how the ROI scan regions 52 are arranged onthe inspection stripe 53 in the actual wafer. (c) and (f) of FIG. 6 areschematic diagrams showing a positional relationship among scanninglines in a visual field region with a size M. (a), (b) and (c) of FIG. 6correspond to a case where a stage movement velocity V0 is equal to aconventional one. (d), (e) and (f) of FIG. 6 correspond to a case wherea stage movement velocity is set to Vs faster than the stage movementvelocity V0. As shown in (b) of FIG. 6, assume that the plurality of theROI scan regions 52 are arranged on the inspection stripe 53 with apitch P and the ROI scan region 52 is formed of n scanning lines of theprimary charged particle beams arranged in a stage movement direction.For the sake of simplicity of description, the length of each ROI scanregion 52 is taken as L, the width of the inspection stripe 53 (thewidth is a measurement in the short-side direction perpendicular to thelong-side direction of the inspection stripe) is taken as I, and thecenter of the inspection stripe (the dotted line in (b) of FIG. 6 istaken as the center of scanning deflection of the primary chargedparticle beam.

In the above case, when capturing all the images on the inspectionstripe 53 with the primary charged particle beam scanning, the stage hasto move only by the distance of one scanning line in the stage movementdirection (the distance is corresponding to one pixel) during the timerequired for scanning of per one scanning line. The time required forscanning of the primary charged particle beam per one scanning line isequal to 1/f with the deflection frequency of the scanning deflector asf. Usually, the detector 13 of the inspection device outputs image datafor one scanning line per the above time of 1/f, so that 1/f is referredto as one-line image capturing time. A normal stage movement velocity V0refers to the velocity at which the sample stage can move by one pixelsize during the time corresponding to the one-line image capturing time.In the present embodiment, the V0 may be represented by the stagemovement velocity synchronized with the beam scanning.

As shown in (b) of FIG. 6, assuming that that plural ROI scan regions 52are arranged on the inspection stripe 53 with a pitch P and the stage iscontinuously moved at the velocity V0, as shown in (c) of FIG. 6, thefirst scanning line 61 a and an n-th scanning line 61 b arranged in theROI scan regions 52 move only by the length corresponding to n pixels,i.e., an actual distance L on the wafer within the range of the visualfield region M. This is because, as described above, the stage movementvelocity is synchronized with the beam scanning speed.

On the other hand, assuming that the stage is moved at a velocity Vsfaster than the stage movement velocity V0, the irradiation position ofthe primary charged particle beam is moved to the adjacent scanning linebefore the scanning of one line is finished, thereby failing to scan animaged position on the actual wafer. More specifically, if the stagemovement velocity Vs is faster than the image capturing speed, it isimpossible to capture the images on the full-inspection stripe 53.However, as shown in (e) of FIG. 6, even at the stage movement velocityVs, when only an image in the intermittently arranged ROI scan region 52has to be captured on the inspection stripe 53, as shown in (f) of FIG.6, if an image-capture is started just when a first scanning line 61 centers the visual field region with a size M (namely, at the point whenthe first scanning line 61 c lies on the left side-edge of the visualfield region M in (f) of FIG. 6) and the final pixel of an n-th scanningline 61 d is completed to be captured while the n-th scanning line 61 dexists in the visual field region M, images can be captured in the ROIscan region 52 without failure, by the following conditions.

The size M of the visual field region is normally maximized within therange of maximum value of visual field determined by the performance ofan electro-optical system. The electro-optical system has a visual fieldwith a certain size and images substantially equivalent in the influenceof aberration and distortion can be captured in the visual field. Themaximum value of the visual field is determined by the performance of anelectro-optical system such as the deflection distance of a scanningdeflector or the degree of aberration of curvature of field. The greaterthe visual field region to be set, the greater the region of a samplewhich can be imaged at one time, thereby enabling a high-speedinspection also in the ROI inspection.

To be more exact,

if the primary charged particle beam irradiation is started at a headpixel in the first scanning line 61 c at the instant when an actualwafer's position to be the head pixel of the first scanning line 61 ccomes into the visual field region M, and

if the primary charged particle beam irradiation is finished at theinstant when an actual wafer's position to be the final pixel of then-th scanning line 61 d comes out of the visual field region M,

the entire ROI scan region 52 can be imaged without failing to capturethe images.

Reference numeral 61 e denotes a first scanning line in the next ROIscan region 52. Hereinafter, the beam is sequentially scanned to the setplurality of ROI scan regions.

In addition, in this case, the stage movement velocity Vs since isasynchronous with the scanning deflection frequency of the beam, thebeam irradiation position in the ROI scan region 52 is graduallydisplaced from the position on the scanning line to be originallyirradiated with the beam with respect to the stage movement direction ifnothing is done. The inspection device of the present embodiment cancelsthe displacement due to asynchronism between the beam scanningdeflection frequency and the stage movement velocity by deflecting backthe irradiation position of the primary charged particle beam to thesame direction as the stage movement direction by a deflecting-backdeflection. This control is realized by the general control section 18causing the scanning deflector 3 to perform the deflecting-backdeflection to cancel the above displacement due to asynchronism.

The aforementioned displacement due to asynchronism increases along withadvancement in the repetition of scanning from the first scanning lineto the n-th scanning line, so that the deflection distance ofdeflecting-back deflection of the primary charged particle beam 2 (thebeam deflection angle of the scanning deflector 3) increases. Thegreater the beam deflection angle of the scanning deflector, the moreadvantageously the stage movement velocity is increased.

However, the stage movement velocity Vs cannot be limitlessly increasedbut is restricted by the ratio of the size M of the visual field regionto the length L of the ROI scan region 52 (substantially, the area ofthe ROI scan region). A mathematical formula 1 given below indicates theabove constraint condition and shows that, if an imaging region with alength L is set in the visual field region with a size M, the stagemovement velocity should be smaller than the right side value of themathematical formula 1 to image throughout the imaging region.Vs≦{(L+M)/L}V0  [mathematical formula 1]

On the other hand, the upper limit of the stage movement velocity isrestricted also by the length L of the ROI scan region 52 and thearrangement pitch P in the stage movement direction in the ROI scanregion 52. The following mathematical formula 2 shows the constraintcondition.Vs≦(P/L)V0  [mathematical formula 2]

If a scan skip region is considered to be provided between the ROI scanregions from which images are captured, the mathematical formulas 1 and2 are understandable. The greater the length of the skip region, thefaster the stage movement velocity can be made. On the other hand, thegreater the width of the ROI scan region, the slower the stage movementvelocity needs to be made. For this reason, the stage movement velocityis set according to the ratio of the width of the scan region to thewidth of the skip region. As shown in (b) and (e) of FIG. 6, if thelength of the ROI scan region 52 is L and the arrangement pitch in thestage movement direction is P, the size of the scan skip region is equalto difference between P and L, namely (P−L). If a scanning skip distanceis taken as S, S is represented by S=P−L, and S=P−L can be rewritten asP=S+L. Substituting P=S+L for the mathematical formula 2 gives thefollowing formula:Vs≦{L+S)/L}V0  [mathematical formula 3]

Apparently, the mathematical formula 3 is equal to the mathematicalformula 1. More specifically, the mathematical formulas 1 and 2 showthat the maximum value of the scan skip region is M−L, i.e., thecondition under which one ROI scan region can be set in the visual fieldwith a size M (the condition under which the beginning edge and endingedge scanning lines in the ROI scan region can exist in the same visualfield M) is the upper limit of the scan skip region; and the increase ofthe number of the ROI scan regions and the area thereof in the visualfield M requires that the stage movement velocity should be reduced byjust that much.

The mathematical formula 3 can be changed into the following formula:Vs−V0=ΔV=(S/L)V0  [mathematical formula 4]This formula shows that the increment of the stage movement velocityfrom V0 in the ROI inspection is determined according to the ratio ofthe length of the skip region to that of the ROI scan region 52 or theratio of visual field size M to the length of the ROI scan region 52.

As described above, it is possible to capture the images to be capturedat a high speed by moving the scanning position of the beam 2 under therestraints of the mathematical formulas 1 and 2 according to the regionwhere images are desired to be captured.

For example, when the width L=10 μm, the visual filed M=100 μm, and thepitch P=60 μm, V≦11×V0 or V≦6×V0 can be obtained from the mathematicalformula 1. This means that, even if the stage is moved at most six timesfaster than the case where full images in the inspection stripe 53 arecaptured, the images can be captured in the ROI capturing region 54.

The above description is made on the premise that the general controlsection 18 executes the stage control. It is needless to say that astage movement control means configured to dedicatedly execute the stagemovement control may be separately provided.

FIG. 7 shows a trial inspection execution screen which is displayed inthe trial inspection in step 306. The trial inspection execution screenincludes a map portion 70 on which the inspection stripe 53 is dividedlydisplayed, an image display portion 71 on which a defect image isdisplayed, and a defect information display portion 72 on which variousattribute information (RDC information) such as conditions for detectingdefects and characteristics of defects is displayed. In FIG. 7, four ROIscan regions 52 indicated by reference numeral 75 are displayed on themap portion 70. A rectangle 76 indicating the ROI capturing region 54and a pointer 73 for highlighting a defect candidate are displayed ineach scan region 75. Although a detailed description is omitted, therectangle 76 indicating the ROI capturing region 54 can be edited byswitching a condition setting tab into an ROI region setting tab 77.Clicking the pointer 73 displays the image and information of a defectcandidate corresponding to the pointer 73 on the image display portion71. Moving the slider of a display threshold setting tool bar 74 allowsselecting the pointer 73 of a defect candidate displayed on the mapportion 70. In other words, information in which a defect candidate canbe selected on condition that the display threshold is lower than acertain value, is predetermined; and by moving the slider in the toolbar, only the defect candidate satisfying the conditions is displayed asitself in accordance with the threshold determined by slider.

The map portion 70 includes a mode for selecting an image display modeof the image display portion 71. There can be switchably displayed theimage of the defect candidate, a part of the captured images stored inthe memory, the images re-captured by moving the stage according to themode. According to the image of the defect candidate, it is possible toconfirm detailed determination of a defect therethrough. According tothe part of the captured images, it is possible to determine whetheranother defect to be detected exists around a certain defect. Accordingto the re-captured images, it is possible to observe whether thedetected defect is a true defect in a case where the detected defect isobserved under an optical condition of a high magnification or a highS/N. Switching the selection mode enables displaying the captured imageitself including the defect candidate on the image display portion 71.The general control of the GUI screen is made by a computing device inthe console 19.

Although not illustrated, by clicking a golden image capturing button,it is possible to re-capture the golden image based on the currentlycaptured image, thereby allowing the image to be updated. By updatingsuch an image or by being selectable as to the image used for averagingin producing the golden image, it is possible to produce a referenceimage with a fewer noise components such as a defect. After theinspection condition is set, information is stored in the recipe, thewafer is unloaded, and the production of the recipe is completed.

FIG. 8 is a diagram describing a method of determining a defect. Thereare several kind of modes in defects of interest (DOI) among the defectsdetected by the inspection device, for example: a black-patternwhite-defect mode in which a hole portion of the contact hole normallyappearing black appears white because of non-conduction; a small-holedefect mode in which a black pattern appears small because the holediameter of the contact hole is reduced; and a white-patternwhite-defect mode in which a plug portion normally appearing white makea short-circuit with an adjacent plug and thereby it appears whiter thanthe normally appearing white. The appearance of the defect pattern isdetermined according to the above modes. As to a nuisance which is anoise desired not to be detected, it typically is exampled as a whitebright-spot defect-mode in which a white bright spot appears in aninsulation-film region due to electrical charges therein.

The defect determination section 17 compares an ROI capturing regionimage 81 with a golden image 80 to produce a first difference image 82with a size of an ROI capturing region including a pixel different inbrightness (whose position coordinates corresponds to the position of adefect candidate) and produces a second difference image 83 in the orderof a region in size including only the vicinity of the position of adefect candidate using the difference image 82.

The defect determination section 17 uses images 84A, 84B, 84C, and 84Dof various defect modes such as previously obtained black-patternwhite-defect mode, small-hole defect mode, and white bright-spotdefect-mode in an insulation film thereby to produce a “reference image85 for determining a matching rate”, the reference image 85 to becompared with the second difference image 83 in terms of the abovevarious defect modes. A plurality of reference images 85 for determininga matching degree are collated with the second difference image 83 tocalculate a matching rate with respect to the various defect modes. Atable 86 shows calculation results of a matching rate corresponding tothe defect modes A to D and also shows that the defect mode A is thehighest in a matching rate.

By selecting the mode being the highest in the matching rate, it ispossible to know the certain defect mode as to the detected defect.Images previously captured for reference image are exampled as follows:namely,

images with a non-conductive defect mode in which the holes' resistancesare the same kind (non-conduction, for example) but the values of theresistances are different from each other, or

images with different defect modes (a non-conductive defect mode inwhich the holes' resistances of the hole are different from each otherand a small hole defect mode in which the diameters of the holes aredifferent from each other, for example)

or

any one of the both different modes.

Therefore, the inspection device of the present embodiment is providedwith a memory for storing image data of the above-mentioned defect modesin the defect determination section 17. According to the presentembodiment, it since is possible to compare images captured to beinspected with a reference sample (reference mode) previously capturedas defect mode, it can obtain information only as to the interestingdefect mode as well as information such as occurrence frequency ofdefect in which any defect mode is not specified or information ofdefect-distribution, by filtering the compared image with any defectmode.

FIG. 9 is a sequence diagram for capturing an image used for thecomparison inspection. FIG. 10 is a graph showing a change in the amountof obtained signals with time. In FIG. 9, a line number (in which thefinally obtained line is numbered in the order of coordinates in a casewhere a single image is captured by a plural number of times of electronbeam scanning) is provided in the vertical direction and a line scanningorder is represented by a number in a square showing an image. Forexample, in a line [1], a data-obtaining is performed four times in thefourth, seventh, tenth, and thirteenth line-scanning orders. These dataare subjected to a weighted averaging. The contents of the weight aredescribed below. In FIG. 10, the amount of signals obtained from thewafer 6 is decreased with the lapse of time. At the beginning, thewafer-surface state can be discriminated and thereafter the amount ofsignals is differently decreased between a normal portion and a defectportion due to a difference in a charging state caused by a differencein the structure of the region irradiated with the primary chargedparticle beam 2. This enables discriminating between the normal portionand the defect portion. Then, the weight of time for which innerinformation of the wafer can be available is increased. Contrarily, theweight of time for which only surface information of the wafer can beobtained is made negative, thereby the process using data added with aweight can provide more accurate information than the process using dataadded without a weight. By executing the inspection using information asto such a signal amount-transient characteristic, the inspectionaccuracy can be improved because of excluding an influence from imagedata including a large amount of surface information and increasing theinner information. The present embodiment is characterized in that theuse of such a transient characteristic increases the inspectionaccuracy.

The above description although is made on the premise that the whole ROIscan region 52 is irradiated with the primary charged particle beam andthe region corresponding to the ROI capturing region 54 is extractedfrom the captured image and inspected, the inspection device may use aconfiguration in which only the ROI capturing region 54 is irradiatedwith the beam at the time of scanning the ROI scan region 52. FIG. 11 isa graph showing a relationship between the image-obtained region and thedeflection voltage applied to the deflector 3 by the inspection devicewith a function of irradiating only the ROI capturing region 54 with thebeam. As an example, described below is a method of controlling aprimary charged particle beam scanning for imaging only regions 110 aand 110 b shown in (a) of FIG. 11. (b) of FIG. 11 shows the timewaveform of a deflection voltage applied to the deflector 3 in a casewhere the whole ROI scan region 52 is imaged. The ordinate shows timeand the abscissa shows the deflection voltage. Since the deflectionvoltage is zero (V) at the center of the scanning deflection, thedeflection voltage is negative at the time of scanning the upper half ofthe ROI scan region 52 shown in (a) of FIG. 11, and the deflectionvoltage is positive at the time of scanning the lower half of the ROIscan region 52.

In the case of imaging only the regions 110 a and 110 b, as shown in (c)of FIG. 11, the deflection voltage applied to the scanning deflector 3at a time of 0 is set to the voltage corresponding to a scanningbeginning position (the upper end portion in the region 110 a) in theregion 110 a. In other words, scanning is started in a state where atime region (i) shown in (b) of FIG. 11 is skipped. The deflectionvoltage increases with time. When the deflection voltage reaches thevoltage corresponding to a scanning ending position in the region 110 a(the lower end portion in the region 110 a), the deflection voltage isstepwise changed to the voltage corresponding to a scanning beginningposition in the region 110 b (the upper end portion in the region 110b). Such a stepwise change corresponds to the skip of a time region (ii)shown in (b) of FIG. 11. Thereafter, the deflection voltage increaseswith time. When the deflection voltage reaches the voltage correspondingto a scanning ending position in the region 110 b (the lower end portionin the region 110 b), scanning of one line is finished. Thereafter, thedeflecting-back deflection control to the stage movement directionresets the deflection voltage to the voltage in a position correspondingto the scan beginning position on the following scanning line. The abovebeam scanning control realizes the ROI control imaging only the regions110 a and 110 b.

The above beam scanning control reduces a scanning time per one scanningline (a beam irradiation time) by time (i)+(ii)+(iii) shown in (c) ofFIG. 11. In other words, the stage movement velocity Vs (substantially,V0) can be made faster by the above reduced time.

The above beam scanning control is realized such that the generalcontrol section 18 computes the time waveform of the deflection voltagebased on the dimension and arrangement pitch of the memory mat 32 andarrangement information about the ROI capturing region 54 on the memorymat and controls the scanning deflector 3 based on the computeddeflection voltage with the time waveform. Although the abovedescription takes, as an example, a beam scanning control method inwhich only the regions 110 a and 110 b including two ROI capturingregions 54 are irradiated with the beam, it is to be understood that thebeam scanning control can also be executed so as not to irradiate theregion expect the ROI capturing region 54 in the regions 110 a and 110b.

As described above, the inspection device of the present embodimentrealizes the inspection device whose inspection speed is much higherthan ever before.

Embodiment 2

The embodiment 1 describes the example in which the ROI capturing region54 is set in the memory mat, a defect in which the device user isinterested may be unevenly distributed in units of structure of a waferlarger in dimension than the visual field of the detection opticalsystem, for example, in units of structure such as a die or a wafer witha dimension of mm order. In the present embodiment, an inspection methodis described in a case where the ROI is set in units of structure largerthan the one in the embodiment 1. The general configuration of theinspection device is substantially similar to that shown in FIG. 1, sothat the description is not repeated.

FIGS. 12A, 12B, and 12C show examples of arrangement of the ROI of thepresent embodiment on the die or the wafer. FIG. 12A is a chart showinga layout of part of the die to be inspected and shows an example wherethe inspection stripe 53 is arranged on the memory mat group 31. In FIG.12A, the ROI being the interesting inspection region is only the memorymat group 31 in the memory mat regions 121 a and 121 b. In other words,the peripheral circuit portion excluding the memory mat group is thin inpattern and low in probability that a defect occurs, so that theperipheral circuit portion is excluded from our interest. FIG. 12B showsan example where the ROI is set in memory mat both-side regions 122 a to122 d. In general, in the region where the rate of change in patterndensity is high, defects tend to frequently occur. Therefore, defectstend to frequently occur in the both side region of the memory matgroup. FIG. 12C shows an example where the ROIs are set in the dicearound the periphery of the wafer. A wafer peripheral die 123 hatched inFIG. 12C causes defects more frequently than a wafer inner die becauseof different conditions for a manufacturing process, so that waferperipheral region dice 124 a and 124 b are truly interesting regions.

In a case where an image is captured only in the aforementioned region,the region for an inspection image is set on the inspection regionsetting screen shown in FIG. 4 and the general control section 18 iscaused to execute a stage movement control according to the informationabout the position in the set region. More specifically, the stagemovement velocity V is made variable, only the above memory mat regions121 a and 121 b, the memory mat both-side regions 122 a to 122 d, thewafer peripheral regions 124 a and 124 b are moved at a low velocity,and the regions other than those are moved at a high velocity. In otherwords, the sample stage is moved at a velocity higher than the velocityat which an image is detected in the region excepting a predeterminedregion on the same inspection stripe. This enables the inspection timeto be made shorter than ever before.

Embodiment 3

In the present embodiment, another modification for setting an ROIcapturing region is described below. The general configuration of theinspection device used in the present embodiment is similar to thatshown in FIG. 1 as is the case with the embodiment 2.

FIG. 13A is a schematic diagram showing the layout of the ROI capturingregions in the memory mat 32 in a case where each of the ROI capturingregion 131 is set larger than the previously mentioned memory mat cornerportion. In FIG. 13A, each of the ROI capturing regions 131 is set as apartial region 131 which is equal to the memory mat in vertical length(namely length in the direction where the beam is scanned) and includesapproximately several memory cells in the length direction of the memorymat (namely, in the stage movement direction). The plurality of partialregions 131 (three partial regions in the present embodiment) arearranged in the length direction of the memory mat. In FIG. 13A, thearea of the partial regions 131 set on the memory mat 32 accounts forapproximately 40% of area of the memory mat. In a case where inspectionimages are sampled from the set region shown in FIG. 13A, there can berealized the stage movement and inspection speed which are faster by 2.5times than those of typical whole surface inspection.

When the above inspection is performed, the visual filed region M is setto such a size as to include at least one memory mat 32 and the generalcontrol section 18 executes the stage control according to the length ofthe partial region 131 in the stage movement direction and the length ofthe skip region between the plurality of partial regions 131. Thepartial regions 131 are set on the inspection region setting screenshown in FIG. 4. A defect detection is executed by a method of using thegolden image described in the embodiment 1 where the same pattern isrepeated in the beam scanning direction and/or the stage movementdirection. Furthermore, a method using an RIA method (described inPatent Document 3 and Non-Patent Document 1) in which the repetitivepatterns are mutually subjected to averaging and the averaging-subjectedimages are arranged and taken as a reference image, and a die comparisonusing the same pattern for each die. As is the case with the embodiment1, the golden image used for defect-detecting comparison computing isproduced with the console 17 by computing the averaging value of theplurality of partial regions 131.

As shown in FIG. 13A, the partial regions 131 are not always set atequally spaced intervals. In that case, the displacement between thescanning line position and the beam irradiation position arranged ineach partial region 131 is cancelled by any of the adjustment of thestage movement velocity or the control of amount of the deflecting-backdeflection. In the case of adopting the adjustment of the stage movementvelocity, there since may be problem in mechanical accuracy, it is moreadvantageous to adopt the control method of the deflecting-backdeflection with high controllability.

FIG. 13B is a schematic diagram showing a layout of the ROI capturingregions set at certain memory mats positioned in a plurality of memorymats forming a memory mat group in a case where each of the certainmemory mats is set as a unit to be detected. In the example shown inFIG. 13B, the ROI capturing regions are set to several certain memorymats respectively at four corners of the memory mat group 31, at themid-points of each side portions of the memory mat group 31, and at thecenter of the memory mat group 31. Furthermore, in a plurality of memorycells constituting each of memory mats selected as the ROI capturingregions as described above, memory cells at only each corner-region inall the memory cells are to be inspected. Thereby, it is possible toincrease the speed of inspection in comparison with that of theembodiment 1 in accordance with the rate of selection of the memorymats.

According to the present embodiment, the inspection time issubstantially made shorter than that in a case where the whole surfaceof the wafer is inspected because both of speed-up by image capturingfor sampling in units of memory mat and speed-up by image capturing forsampling with specifying corner portions in the memory mat.

In the case of inspecting under the condition setting the ROI capturingregions shown in FIG. 13( b), required is the following two kinds ofcontrol parameters: one is a control parameter for performing the beamscanning control and the stage movement control in the memory mat 32;another is a control parameter for performing the beam scanning controland the stage movement control in a case where the visual filed region Mis on the order of the memory mat group 31. More specifically, there arerequired parameters: information about the layout of corner portions(information about size and position of the rectangular region 44 shownin FIG. 4) and information about the dimension of the memory matrequired for capturing images, only at the corner portions in the memorymat; information about the layout of memory mats specified in units inthe memory mat group 31 to perform a sampling inspection (namely theinformation is about size and position of the specified memory mat inthe memory mat group 31) and information about the dimension of thememory mat group. The above control parameters may be set through theGUI by appropriately switching the visual field size of the image to bedisplayed on the image display region 42 of the inspection regionsetting screen shown in FIG. 4. The set control information istransferred to the general control section 18 and used for the beamscanning control and the stage movement control.

Even if the above sampling is performed and if the occurrence of adefect is distributed, it is possible to capture the distribution. Thepresent modification has an advantage in that a required defectdistribution can be obtained and the inspection time can be made furthershorter than ever before.

Embodiment 4

In the present embodiment, still another modification for setting theROI capturing region is described below. FIG. 14 shows the relationshipof layout in a case where three ROI capturing regions are set in onememory mat. That is, in this embodiment, in order to inspect partiallyspecified regions in the memory mat 32, the inspection is done byspecifying the plural ROI capturing regions 54 to be irradiated forscanning with the charged particle beam in order by arrangement in thestage movement direction, and by scanning the specified ROI capturingregions in their arrangement order with the charged particle beamirradiation and the stage movement.

A plurality of memory mats 32 are arranged on the wafer, so that the ROIcapturing regions 54 are regularly arranged in sequential inspectionregion 141. In addition, in a non-inspection region 142 including nearan inspection start side-edge portion of the die and wide gaps existingin the arrangement of the memory mats 32, dummy inspection regions 143are arranged as densely as the sequential inspection region 141. This“as densely as the sequential inspection region” means that the dummyinspection regions 143 are arranged based on a logic similar to thearrangement of the ROI capturing regions 54 by virtually assuming therepetition of the memory mat or the repetition of the die, or means thatthe dummy inspection regions 143 are arranged at regular intervalsdetermined in accordance with the stage-velocity.

The arrangement of the dummy inspection regions enables electro staticcharge on the wafer 6 to be uniformly held by beam irradiation.

The dummy inspection regions 143 may be captured as images or may beonly irradiated with the charged particle beam. The same effect can beexpected by increasing the scanning interval of each charged particlebeam instead of arranging the dummy inspection region 143 at regularintervals. It is needless to say that the same effect can be expected byperforming scanning incompletely with the scanning interval of thecharged particle beam increased, instead of completely scanning evenbetween the ROI capturing regions 54.

In the above embodiments 1 to 4, description although is made using amethod in which a defect is detected by comparing a previously obtainedgolden image 45 with a captured image of interest as to defectdetection, any defect detection method may also be used such as actualpattern comparison methods such as cell comparison, RIA method, diecomparison, and mat comparison, and a comparison method with a designpattern generated from design.

According to the present embodiment, it is possible to provide theinspection system capable of making high-speed image capturing timealmost six times as speed as time required for normally capturing animage on a whole surface of the wafer and capable of inspecting a defectoccurrence frequency distribution in the ROI region at a highthroughput. Furthermore, the present embodiment can provide theinspection device and method for efficiently monitoring a defectoccurrence frequency and a characteristic likelihood.

DESCRIPTION OF SYMBOLS

-   2: Primary charged particle beam, 3: Deflector, 4: Object lens, 5:    Charging control electrode, 6: Wafer, 7: X-Y stage, 8: Z-sensor, 9:    Sample table, 10: Secondary signal, 17: Defect determination    section, 18: General control section, 19: Console, 20: Optical    microscope, 21: Reference sample, 30: Die, 31: Memory mat group, 32:    Memory mat, 33: Memory cell, 41: Map display region, 42: Image    display region, 43: ROI condition setting section, 44: Rectangular    region, 52: ROI scan region, 53: Inspection stripe, 54: ROI    capturing region, 70: Map, 71: Image display portion, 72: Defect    information display portion, 73: Mark, 74: Display threshold setting    toolbar, 80: ROI capturing region image, 81: Golden image, 82:    Difference image

The invention claimed is:
 1. A charged particle beam device for scanninga sample using a charged particle beam to inspect the sample, the sampleplaced on a sample stage and having a plurality of pattern-regions eachwhere a predetermined pattern is formed, wherein: the device isconfigured to scan the sample using the charged particle beam in adirection intersecting a sample stage-movement direction and capture animage based on signals obtained by detecting a secondary electron or areflection electron generated on the sample by the scanning; the deviceis configured to inspect the sample using the captured image, the deviceincludes a charged particle column including a scanning deflector forcontrolling the scanning direction of the charged particle beam, and acontrol section for controlling a movement velocity of the sample stage,the device is configured to set a plurality of scan regions arrangedintermittently in an inspection stripe extended on the sample in amovement direction of the sample stage, the plurality of scan regionswhich are to be scanned by the charged particle beam for the capturedimage, the device is configured to set a plurality of partial inspectionregions in each of the scan regions through a screen of a console,wherein each of the partial inspection regions includes edges to beinspected partially in each of ions on the sample, and the device isconfigured to sample the plurality of partial inspection regionsincluding the edges from each of the scan regions by the scanning whilethe stage is being moved to capture the inspection image from thepartial inspection regions.
 2. The charged particle beam deviceaccording to claim 1, wherein the device is further configured to selectthe partial inspection regions including a first scan region and asecond scan region, the first scan region from which a first image iscaptured by the scanning, and the second scan region from which a secondimage is captured later than the first image; and wherein the controlsection is configured to set the sample stage-movement velocity so thata scan ending edge of the first scan region and a scan beginning edge ofthe second scan region fall within a visual field in which aberrationsand distortions of the scan ending edge and the scan beginning edge areregarded as the same respectively in a range of the charged particlebeam scanning in the sample stage-movement direction.
 3. The chargedparticle beam device according to claim 1, wherein the device isconfigured to set a scan skip region between the partial inspectionregions, the scan skip region where the scanning is not executed by askip.
 4. The charged particle beam device according to claim 1, whereinthe charged particle column is configured to execute the scanning whiledeflecting the charged particle beam in the same direction as the samplestage-movement direction to irradiate the inspection region selected bythe sampling with the charged particle beam.
 5. The charged particlebeam device according to claim 1, further comprising: a screen displaysection for displaying a region setting screen for the sampling.
 6. Thecharged particle beam device according to claim 1, wherein the samplestage is configured to place a semiconductor wafer on which a pluralityof memory mats are formed, each memory mat being composed of a pluralityof memory cells.
 7. The charged particle beam device according to claim6, further comprising: a display section for displaying a region settingscreen for the sampling, the region setting screen being equipped with adisplay window on which one memory mat out of the plurality of memorymats is displayed, wherein the inspection region to be sampled set onthe displayed memory mat is developed to another memory mat based on theregularity of arrangement of the memory cell to sample the pluralinspection regions.
 8. A charged particle beam device for scanning asample using a charged particle beam to inspect the sample, the sampleplaced on a sample stage and having a plurality of pattern-regions eachwhere a predetermined pattern is formed, wherein: the device isconfigured to scan the sample using the charged particle beam in adirection intersecting a sample stage-movement direction and capture animage based on signals obtained by detecting a secondary electron or areflection electron generated on the sample by the scanning; the deviceconfigured to inspect the sample using the captured image; the deviceincludes a control section for controlling a movement velocity of thesample stage; the device is configured to set a first scan region, asecond scan region and a scan skip region in each of thepattern-regions, the first and second scan regions each where aplurality of scanning lines with the beam run sequentially for thescanning and the scan skip region where the scanning is not executed bya skip, wherein the scan skip region is arranged between the first andsecond scan regions; and the control section is configured to set thesample stage-movement velocity so that a scan ending edge of the firstscan region and a scan beginning edge of the second scan region fallwithin a visual field in which aberrations and distortions of the scanending edge and the scan beginning edge are regarded as the samerespectively in a range of the charged particle beam scanning in thesample stage-movement direction.
 9. The charged particle beam deviceaccording to claim 8, wherein the control section is configured tocontrol the sample stage-movement velocity so that a width of each ofthe partial inspection regions in the sample-stage movement directionfalls within the visual field.
 10. A charged particle beam device forscanning a sample using a charged particle beam to inspect the sample,the sample placed on a sample stage and having a plurality ofpattern-regions each where a predetermined pattern is formed wherein:the device is configured to scan the sample using the charged particlebeam in a direction intersecting a sample stage-movement direction andcapture an image based on signals obtained by detecting a secondaryelectron or a reflection electron generated on the sample by thescanning; the device is configured to inspect the sample using thecaptured image; the device includes a control section for controlling amovement velocity of the sample stage; the device is configured to set ascan region and a scan skip region in each pattern-region, the scanregion where plural scanning lines with the beam run sequentially forthe scanning and the scan skip region where the scanning is not executedby a skip; and the control section is configured to set the samplestage-movement velocity in accordance with a ratio of a width of thescan region to a width of the scan skip region in the samplestage-movement direction.